Port tests.yml workflow file from 3.3.x

Author: marc1706

.github/workflows/tests.yml

@@ -0,0 +1,32 @@
+name: Test make documentation
+
+on:
+  push:
+    branches:
+      - master
+      - '[34].[0-9]+.x'
+  pull_request:
+    branches:
+      - master
+      - '[34].[0-9]+.x'
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up Python
+        uses: actions/setup-python@v2
+        with:
+          python-version: '3.x'
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install sphinx
+          pip install sphinx_rtd_theme
+          pip install sphinxcontrib-phpdomain
+          pip install git+https://github.com/marc1706/sphinx-php.git
+      - name: Test make html
+        run: |
+          cd development
+          make html